The theoretical framework that describes the properties of semiconductors and insulators dates back to the times of
the foundation of quantum mechanics. It has proved to be very successful - a good deal of modern semiconductor industry relies on
these early developments. However, about eight years ago it was realised that important aspects of the physics of certain
semiconductors could not be explained by the existing theory and an enhanced band theory, called "topological band theory" is needed.
The materials covered by this new theory are called "topological insulators" and they are in the focus of a very intensive current research effort.
Concepts of topological band theory have since appeared in other fields of physics as well, e.g., in particle physics and string theory.

In this seminar we are planning to cover the basic ingredients of this enhanced band theory. The emphasis will be on the understanding
of core concepts with as simple mathematical tools as possible. We will also discuss the solid state physics background that is needed to
place these concepts into a wider context.